1. Field of the Invention
The present invention relates to a flat cutting blade for use in a cutting machine and, more particularly, to a cutting blade for cutting a sheet-like substrate such as a ceramic green sheet.
2. Description of Related Art
There is a cutting machine suitable for getting a plurality of chips by cutting, into a form of checkers, a sheet-like substrate (material sheet) such as a ceramic green sheet before sintering. The cutting machine is designed to cut with a flat cutting blade pressed like a guillotine against a work at a given spacing (pitch feed). The overall cutting section of the cutting blade thus used is formed in a shape of a sharp V-edge in a front view.
With a recent tendency to down-size electronic equipment, there has been a demand for small chips measuring for example 0.6 mm long by 0.3 mm wide. To cut a work by pressing a guillotine type double-edged cutting blade mentioned above while maintaining a given working accuracy, it becomes necessary to decrease the edge angle to minimize deformation of a cut surface of the work.
This type of cutting blade, therefore, is provided with a edge angle of around 10 deg. to 30 deg. and a shank thickness of around 1 mm.
This type of cutting blade is detachably mounted on a vertically movable tool holder of a cutting machine not depicted, and a centering camera is mounted on a supporting body of the tool holder, so that the centering camera will make an exposure of a pair of line marks provided in opposite positions at an equal spacing on the edges of a work (on four edges in the case of a rectangular work) every time the work is fed for a specific amount each pitch. Furthermore an image thus obtained is processed to center the line marks, and, after moving by the amount of correction to correct an index table on which the work is held by adsorption, the cutting blade is fed downwardly to cut the work.
This operation is repeated every time of pitch feed in a given direction of length of the work, and after the completion of operation in one direction, the work W on the index table is turned through 90 degrees and is cut in a like manner as described above, thereby making chips.
At this time, the four edges carrying the line marks are unsuitable for use as cut chips because of the presence of the line marks. Therefore, it is a mainstream of a cutting method to cut a work into a form of checkers, leaving the cutting edge portion of the work in the form of a frame.
However, if the edge angle is formed much smaller without altering the blade thickness (thickness of the shank portion), the surface area of the edge surfaces (cutting portion) on both right and left sides naturally increases; and both the right and left sides work as a great resistance at the time of cutting. Therefore a great cutting force is needed at the time of cutting, with the result that the cutting edge portion will be subjected to buckling deformation.